1 //===-- LLVMTargetMachine.cpp - Implement the LLVMTargetMachine class -----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the LLVMTargetMachine class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Target/TargetMachine.h"
15 #include "llvm/Analysis/Passes.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/BasicTTIImpl.h"
18 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
19 #include "llvm/CodeGen/MachineModuleInfo.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/CodeGen/TargetPassConfig.h"
22 #include "llvm/IR/IRPrintingPasses.h"
23 #include "llvm/IR/LegacyPassManager.h"
24 #include "llvm/IR/Verifier.h"
25 #include "llvm/MC/MCAsmInfo.h"
26 #include "llvm/MC/MCContext.h"
27 #include "llvm/MC/MCInstrInfo.h"
28 #include "llvm/MC/MCStreamer.h"
29 #include "llvm/MC/MCSubtargetInfo.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/FormattedStream.h"
33 #include "llvm/Support/TargetRegistry.h"
34 #include "llvm/Target/TargetLoweringObjectFile.h"
35 #include "llvm/Target/TargetOptions.h"
36 #include "llvm/Transforms/Scalar.h"
37 using namespace llvm;
38 
39 // Enable or disable FastISel. Both options are needed, because
40 // FastISel is enabled by default with -fast, and we wish to be
41 // able to enable or disable fast-isel independently from -O0.
42 static cl::opt<cl::boolOrDefault>
43 EnableFastISelOption("fast-isel", cl::Hidden,
44   cl::desc("Enable the \"fast\" instruction selector"));
45 
46 static cl::opt<bool>
47     EnableGlobalISel("global-isel", cl::Hidden, cl::init(false),
48                      cl::desc("Enable the \"global\" instruction selector"));
49 
50 void LLVMTargetMachine::initAsmInfo() {
51   MRI = TheTarget.createMCRegInfo(getTargetTriple().str());
52   MII = TheTarget.createMCInstrInfo();
53   // FIXME: Having an MCSubtargetInfo on the target machine is a hack due
54   // to some backends having subtarget feature dependent module level
55   // code generation. This is similar to the hack in the AsmPrinter for
56   // module level assembly etc.
57   STI = TheTarget.createMCSubtargetInfo(getTargetTriple().str(), getTargetCPU(),
58                                         getTargetFeatureString());
59 
60   MCAsmInfo *TmpAsmInfo =
61       TheTarget.createMCAsmInfo(*MRI, getTargetTriple().str());
62   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
63   // and if the old one gets included then MCAsmInfo will be NULL and
64   // we'll crash later.
65   // Provide the user with a useful error message about what's wrong.
66   assert(TmpAsmInfo && "MCAsmInfo not initialized. "
67          "Make sure you include the correct TargetSelect.h"
68          "and that InitializeAllTargetMCs() is being invoked!");
69 
70   if (Options.DisableIntegratedAS)
71     TmpAsmInfo->setUseIntegratedAssembler(false);
72 
73   if (Options.CompressDebugSections)
74     TmpAsmInfo->setCompressDebugSections(DebugCompressionType::DCT_ZlibGnu);
75 
76   TmpAsmInfo->setRelaxELFRelocations(Options.RelaxELFRelocations);
77 
78   if (Options.ExceptionModel != ExceptionHandling::None)
79     TmpAsmInfo->setExceptionsType(Options.ExceptionModel);
80 
81   AsmInfo = TmpAsmInfo;
82 }
83 
84 LLVMTargetMachine::LLVMTargetMachine(const Target &T,
85                                      StringRef DataLayoutString,
86                                      const Triple &TT, StringRef CPU,
87                                      StringRef FS, TargetOptions Options,
88                                      Reloc::Model RM, CodeModel::Model CM,
89                                      CodeGenOpt::Level OL)
90     : TargetMachine(T, DataLayoutString, TT, CPU, FS, Options) {
91   CodeGenInfo = T.createMCCodeGenInfo(TT.str(), RM, CM, OL);
92 }
93 
94 TargetIRAnalysis LLVMTargetMachine::getTargetIRAnalysis() {
95   return TargetIRAnalysis([this](const Function &F) {
96     return TargetTransformInfo(BasicTTIImpl(this, F));
97   });
98 }
99 
100 MachineModuleInfo &
101 LLVMTargetMachine::addMachineModuleInfo(PassManagerBase &PM) const {
102   MachineModuleInfo *MMI = new MachineModuleInfo(*getMCAsmInfo(),
103                                                  *getMCRegisterInfo(),
104                                                  getObjFileLowering());
105   PM.add(MMI);
106   return *MMI;
107 }
108 
109 void LLVMTargetMachine::addMachineFunctionAnalysis(PassManagerBase &PM,
110     MachineFunctionInitializer *MFInitializer) const {
111   PM.add(new MachineFunctionAnalysis(*this, MFInitializer));
112 }
113 
114 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
115 static MCContext *
116 addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
117                         bool DisableVerify, AnalysisID StartBefore,
118                         AnalysisID StartAfter, AnalysisID StopAfter,
119                         MachineFunctionInitializer *MFInitializer = nullptr) {
120 
121   // When in emulated TLS mode, add the LowerEmuTLS pass.
122   if (TM->Options.EmulatedTLS)
123     PM.add(createLowerEmuTLSPass(TM));
124 
125   PM.add(createPreISelIntrinsicLoweringPass());
126 
127   // Add internal analysis passes from the target machine.
128   PM.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
129 
130   // Targets may override createPassConfig to provide a target-specific
131   // subclass.
132   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
133   PassConfig->setStartStopPasses(StartBefore, StartAfter, StopAfter);
134 
135   // Set PassConfig options provided by TargetMachine.
136   PassConfig->setDisableVerify(DisableVerify);
137 
138   PM.add(PassConfig);
139 
140   PassConfig->addIRPasses();
141 
142   PassConfig->addCodeGenPrepare();
143 
144   PassConfig->addPassesToHandleExceptions();
145 
146   PassConfig->addISelPrepare();
147 
148   MachineModuleInfo &MMI = TM->addMachineModuleInfo(PM);
149   TM->addMachineFunctionAnalysis(PM, MFInitializer);
150 
151   // Enable FastISel with -fast, but allow that to be overridden.
152   TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
153   if (EnableFastISelOption == cl::BOU_TRUE ||
154       (TM->getOptLevel() == CodeGenOpt::None &&
155        TM->getO0WantsFastISel()))
156     TM->setFastISel(true);
157 
158   // Ask the target for an isel.
159   if (LLVM_UNLIKELY(EnableGlobalISel)) {
160     if (PassConfig->addIRTranslator())
161       return nullptr;
162 
163     // Before running the register bank selector, ask the target if it
164     // wants to run some passes.
165     PassConfig->addPreRegBankSelect();
166 
167     if (PassConfig->addRegBankSelect())
168       return nullptr;
169 
170   } else if (PassConfig->addInstSelector())
171     return nullptr;
172 
173   PassConfig->addMachinePasses();
174 
175   PassConfig->setInitialized();
176 
177   return &MMI.getContext();
178 }
179 
180 bool LLVMTargetMachine::addPassesToEmitFile(
181     PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
182     bool DisableVerify, AnalysisID StartBefore, AnalysisID StartAfter,
183     AnalysisID StopAfter, MachineFunctionInitializer *MFInitializer) {
184   // Add common CodeGen passes.
185   MCContext *Context =
186       addPassesToGenerateCode(this, PM, DisableVerify, StartBefore, StartAfter,
187                               StopAfter, MFInitializer);
188   if (!Context)
189     return true;
190 
191   if (StopAfter) {
192     PM.add(createPrintMIRPass(errs()));
193     return false;
194   }
195 
196   if (Options.MCOptions.MCSaveTempLabels)
197     Context->setAllowTemporaryLabels(false);
198 
199   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
200   const MCAsmInfo &MAI = *getMCAsmInfo();
201   const MCRegisterInfo &MRI = *getMCRegisterInfo();
202   const MCInstrInfo &MII = *getMCInstrInfo();
203 
204   std::unique_ptr<MCStreamer> AsmStreamer;
205 
206   switch (FileType) {
207   case CGFT_AssemblyFile: {
208     MCInstPrinter *InstPrinter = getTarget().createMCInstPrinter(
209         getTargetTriple(), MAI.getAssemblerDialect(), MAI, MII, MRI);
210 
211     // Create a code emitter if asked to show the encoding.
212     MCCodeEmitter *MCE = nullptr;
213     if (Options.MCOptions.ShowMCEncoding)
214       MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
215 
216     MCAsmBackend *MAB =
217         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
218     auto FOut = llvm::make_unique<formatted_raw_ostream>(Out);
219     MCStreamer *S = getTarget().createAsmStreamer(
220         *Context, std::move(FOut), Options.MCOptions.AsmVerbose,
221         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, MCE, MAB,
222         Options.MCOptions.ShowMCInst);
223     AsmStreamer.reset(S);
224     break;
225   }
226   case CGFT_ObjectFile: {
227     // Create the code emitter for the target if it exists.  If not, .o file
228     // emission fails.
229     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
230     MCAsmBackend *MAB =
231         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
232     if (!MCE || !MAB)
233       return true;
234 
235     // Don't waste memory on names of temp labels.
236     Context->setUseNamesOnTempLabels(false);
237 
238     Triple T(getTargetTriple().str());
239     AsmStreamer.reset(getTarget().createMCObjectStreamer(
240         T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
241         Options.MCOptions.MCIncrementalLinkerCompatible,
242         /*DWARFMustBeAtTheEnd*/ true));
243     break;
244   }
245   case CGFT_Null:
246     // The Null output is intended for use for performance analysis and testing,
247     // not real users.
248     AsmStreamer.reset(getTarget().createNullStreamer(*Context));
249     break;
250   }
251 
252   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
253   FunctionPass *Printer =
254       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
255   if (!Printer)
256     return true;
257 
258   PM.add(Printer);
259 
260   return false;
261 }
262 
263 /// addPassesToEmitMC - Add passes to the specified pass manager to get
264 /// machine code emitted with the MCJIT. This method returns true if machine
265 /// code is not supported. It fills the MCContext Ctx pointer which can be
266 /// used to build custom MCStreamer.
267 ///
268 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
269                                           raw_pwrite_stream &Out,
270                                           bool DisableVerify) {
271   // Add common CodeGen passes.
272   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr,
273                                 nullptr);
274   if (!Ctx)
275     return true;
276 
277   if (Options.MCOptions.MCSaveTempLabels)
278     Ctx->setAllowTemporaryLabels(false);
279 
280   // Create the code emitter for the target if it exists.  If not, .o file
281   // emission fails.
282   const MCRegisterInfo &MRI = *getMCRegisterInfo();
283   MCCodeEmitter *MCE =
284       getTarget().createMCCodeEmitter(*getMCInstrInfo(), MRI, *Ctx);
285   MCAsmBackend *MAB =
286       getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
287   if (!MCE || !MAB)
288     return true;
289 
290   const Triple &T = getTargetTriple();
291   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
292   std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
293       T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
294       Options.MCOptions.MCIncrementalLinkerCompatible,
295       /*DWARFMustBeAtTheEnd*/ true));
296 
297   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
298   FunctionPass *Printer =
299       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
300   if (!Printer)
301     return true;
302 
303   PM.add(Printer);
304 
305   return false; // success!
306 }
307